The 42-year-old Moscow native is much more of a businessman than a spaceman, with years of experience in the tobacco and coffee trade. But for the past five years, he's been the Moscow vice president for Space Adventures, the Virginia-based company that has organized three multimillion-dollar private trips to the international space station. And it's in that capacity that he's serving as the backup cosmonaut for New Jersey
space millionaire Greg Olsen
, who is due to blast off this weekend on a Russian Soyuz craft.

If for some reason Olsen isn't able to get on board at Russia's Baikonur Cosmodrome in Kazakhstan — which, with one day left before launch, seems extremely unlikely — Kostenko is the designated person to take his place. But what would happen to the $20 million that Olsen is paying for the 10-day space station trip?

"I don't want to discuss financial terms," he told MSNBC.com earlier this month at Russia's Star City cosmonaut training complex. "We have a very, very complicated contract. But I am sure Greg Olsen will fly in space."

He said he has absolutely no wish to go in his client's place. "I wish for Greg to be flying in space," he said.

Kostenko said his selection as a backup cosmonaut "was Greg's choice" and also serves Space Adventures' business purposes.

"I wanted to try all the space training experiences," he said. "It's not bad for my contacts with potential orbital clients. We have some new technical projects, and I need to know from the inside exactly what's happening in space."

Four months of training
That meant Kostenko had to shadow Olsen through four months of training — including "too many medical checks," in his opinion.

"I passed the same tests, the same exams as Gregory, and I'm staying with him all the time," Kostenko said.

That's common practice for spaceflights, and even the professional astronauts on Olsen's flight — NASA's Bill McArthur and Russia's Valery Tokarev — have backups: Jeffrey Williams for McArthur, and Mikhail Tyurin for Tokarev. At formal news conferences, the three backups sit beside the primary crew, but rarely get a chance to field a question.

If a switch had to be made, would Kostenko really go into space, or would he sit this trip out? Once again, he skirted the issue.

"It's a very, very, very difficult question, truly," Kostenko said, "because on one side, all backups wish all the main crew members a good launch, a good flight. But on the other side, we're always ready to fly instead."

Back to business
Once Olsen flies, Kostenko plans to return full-time to Space Adventures' business dealings, including the development of a Russian suborbital spaceship for tourist flights, known as the Cosmopolis XXI, or C-21. The C-21 rocket plane would be launched from a modified Russian M-55 carrier aircraft, with a flight profile similar to that of the privately developed SpaceShipOne rocket plane.

The C-21 project has been on hold for months while Space Adventures sought out investors.

"This is like a sleeping project still," Kostenko said, "but we already found all the necessary investment, and probably in the next two months we will inform everybody about big changes in our Russian project."